Any thoughts?

solution:
check for collisions along the _path_ of the ball from current position to next position. if collision happens set ball to point of collision and change velocity.

there r 3 ways to fix this

1- increase the size of the ball, as already mentioned by “J. Cohen”
2- slow down the ball on the Y axis

(those 2 solutions make the intersection happen before the ball’s center passes the paddle)

3- just remove the center checking condition and change the direction directly on collision (which i don’t prefer)

I am also getting a ‘touchesMoved’ undeclared error, ( whatever I place as the second section gets this undeclared error)

Thank you so much, I would be very grateful if you could help with these problems,

The Code is below,

#import “iTennisViewController.h”
#define kCompMoveSpeed 15
#define kGameStateRunning 1
#define kGameStatePaused 2

#define kScoreToWin 5

#define kBallSpeedX 10
#define kBallSpeedY 15

@implementation iTennisViewController
@synthesize ball,racquet_yellow,racquet_green,player_score,computer_score,gameState,ballVelocity,tapToBegin;

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
if(gameState == kGameStatePaused) {
tapToBegin.hidden = YES;
gameState = kGameStateRunning;
} else if(gameState == kGameStateRunning) {
[self touchesMoved:touches withEvent:event];
}

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
UITouch *touch = [[event allTouches] anyObject];
CGPoint location = [touch locationInView:touch.view];
CGPoint xLocation = CGPointMake(Location.x.racquet_yellow.center.y);
racquet_yellow.center = xLocation;
}

-(void) gameLoop {
if(gameState == kGameStateRunning) {

ball.center = CGPointMake(ball.center.x + ballVelocity.x , ball.center.y + ballVelocity.y);

if(ball.center.x > self.view.bounds.size.width || ball.center.x self.view.bounds.size.height || ball.center.y < 0) {
ballVelocity.y = -ballVelocity.y;
}
// Crash detection CGRectIntersectsRect.

if(CGRectIntersectsRect(ball.frame,racquet_yellow.frame)){
if(ball.center.y < racquet_yellow.center.y) {
ballVelocity.Y = -ballVelocity.y;

}
}
if(CGRectIntersectsRect(ball.frame,racquet_green.frame)){
if(ball.center.y < racquet_green.center.y) {
ballVelocity.Y = -ballVelocity.y;
} else {
if(tapToBegin.hidden) {
tapToBegin.hidden = NO;
}
}

// Begin Simple AI}
if(ball.center.y <= self.view.center.y){
if(ball.center.x racquet_green.center.x){
CGPoint compLocation = CGPointMake(racquet_green.center.x + kCompMoveSpeed, racquet_green.center.y);
racquet_green.center = compLocation;
}
}
// Begin Scoring Game Logic}
if(ball.center.y = >= kScoreToWin)]:
}

if(ball.center.y > self.view.bounds.size.height) {
computer_score_value++;
[self reset:(computer_score_value >= kScoreToWin)];
}

-(void)reset:(BOOL)newGame{
self.gameState = kGameStatePaused;
ball.center = self.view.center;
if(newGame) {
If (computer_score_value > player_score_value) {
tapToBegin.text =@”Computer Wins”;
} else {
tapToBegin.text =@”Player Wins!”;

}
computer_score_value = 0;
player_score_value = 0;

} else {
tapToBegin.text = @”Tap to Begin”;
}
player_score.text = [NSString stringWithFromat:@"%d", player_score_value];
computer_score.text = [NssString stringWithFromat:@"%d",computer_score_value];
}

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
[super viewDidLoad];
self.gameState = kGameStatePaused;
ballVelocity = CGPointMake(kBallSpeedX,kBallSpeedY);
[NSTimer scheduledTimerWithTimeInterval:0.05 target:self selector:@selector(gameLoop) userInfo:nil repeats:YES];
}

/*
// Override to allow orientations other than the default portrait orientation.
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
*/

- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning]; // Releases the view if it doesn’t have a superview
// Release anything that’s not essential, such as cached data
}

- (void)dealloc {
[super dealloc];
[ball release];
[racquet_green release];
[racquet_yellow release];
[player_score release];
[computer_score release];
[tapToBegin release];
}

}
}
}
}

@end

and at the end of the code, at the last line after all the dealloc part :
….
}
@end /!\ Incomplete implementation of class ‘ItennisViewController’ (2)

Can somebody help me? Thanks all and thanks for the tutorial!

Improve collision detection – When the ball hits the paddle, use some simple physics to make the speed of the paddle affect the speed (and direction) of the ball.

What I’m trying to do is to make it so that:
- Every time the ball hits the paddle it increases the speed a little.
- The ball’s deflection angle determined by how far is the ball from the center of the paddle when it hits.

Can anyone help me on these?

//
// iTennisViewController.m
// iTennis
//
// Created by ed on 4/5/10.
// Copyright __MyCompanyName__ 2010. All rights reserved.
//

#import “iTennisViewController.h”

#define kScoreToWin 5
-(void) gameLoop{// Begin Scoring Game Logic}
if(ball.center.y = kScoreToWin)];
}
}
if(ball.center.y > self.view.bounds.size.height) {
computer_score_value++;
[self reset:(player_score_value >= kScoreToWin)];

#define kCompMoveSpeed 15
- (void) gameLoop{ // Begin Simple AI}
if(ball.center.y <= self.view.center.y){
if(ball.center.x racquet_green.center.x){
CGPoint compLocation = CGPointMake(racquet_green.center.x + kCompMoveSpeed, racquet_green.center.y);
racquet_green.center = compLocation;
}
}

#define kGameStateRunning 1
#define kGameStatePaused 2

#define kBallSpeedX 10
#define kBallSpeedY 15

@implementation iTennisViewController
@synthesize ball,raquet_yellow,raquet_green,player_score,computer_score,gameState,ballVelocity,tapToBegin;

-(void) gameLoop {
if(gameState == kGameStateRunning) {

ball.center = CGPointMake(ball.center.x + ballVelocity.x , ball.center.y +ballVelocity.y);

if(ball.center.x > self.view.bounds.size.width || ball.center.x self.view.bounds.size.height || ball.center.y <0){
ballVelocity.y = -ballVelocity.y;
}
} else {
if(tapToBegin.hidden){
tapToBegin.hidden = NO;
}
}
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
if(gameState == kGameStatePaused) {
tapToBegin.hidden = YES;
gameState = kGameStateRunning;
}
}

- (void)dealloc {
[super dealloc];
[ball release];
[raquet_green release];
[raquet_yellow release];
[player_score release];
[computer_score release];
[tapToBegin release];
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
if(gameState == kGameStatePaused) {
tapToBegin.hidden = YES;
gameState = kGameStateRunning;
} else if(gameState == kGameStateRunning) {
[self touchesMoved:touches withEvent:event];
}
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [[event allTouches] anyObject];
CGPoint location = [touch locationInView:touch.view];
CGPoint xLocation = CGPointMake(location.x,raquet_yellow.center.y);
racquet_yellow.center = xLocation;
}

When you make the racquet too small the interaction method (CGRectInteractsRect…) never
gets an intersection between racquet and ball.

Buuuuut
Very very very nice tutorial

I had the same problem, so instead of using the “self.view.center” I used the actual values…

ball.center = CGPointMake(160,230);

That way the ball is properly centered…

Best,
Rfl

Anyway, the point was to say check if the gesture’s y location is below or above the net, then move the according paddle.

I have not tried this. I’m busy looking for an answer to my won problem

I wish I understood why. Strangest thing is it worked off the computer’s paddle, but just went right through mine.

UITouch *touch = [[event allTouches] anyObject];
CGPoint location = [touch locationInView:self.view];
if ([touch view] == racquet_green) {
// move the image view
racquet_green.center = location;
}
if ([touch view] == racquet_yellow) {
// move the image view

racquet_yellow.center = location;
}

but still

you need to put the

//Begin Simple AI
if stmt inside the -(void) gameLoop { }
method

then its all good

Xcode says: error: expected identifier or ‘(‘ before ‘if’ in: ViewController.m

// Begin Simple AI

if(ball.center.y <= self.view.center.y) {

What's wrong?

plz reply